I am looking for the correct english term that can best be explained as follows:
You are producing clothes. One day you get the wrong color on the fabric that you have ordered, and thus you need to create a report about this error.
What is this report called? Deviation report? Aberration? Disparity? Something else?
(What I’m looking for in Swedish is “Avvikelserapport”, if some Swede sees this and immediately knows the correct term.)
Tia,
Andreas 
Isn’t that used in the IT sector? I am thinking about failing hard drives etc… 
Error Report?
20 chars
Incident report where I work.
Non conformity or discrepancy.
to me it would be a ‘mispick’:
What is a Mispick in a warehouse?
A mispick occurs when someone in your warehouse fails to pick products precisely as listed on a picking document or as guided by warehouse management software.
That’s what it should be recorded as on the supplier systems.
At last a topic about my day job 
I would call it an exception.
I would enter the appropriate Reason Code from a list on the Return and Exchange form that accompanies many items purchased Mail Order or Online.
I would go with what @geoffaire has suggested.
Also I would have a look into the contract between you, and your subcontractor. Often there are certain terms used in those contracts, that should be also been used with the complaint.
Couple of additional options:
Compliance report
Conformance (or non-conformance) report
Thanks folks! A lot of good suggestions, I will propose some of these to my client.
Thanks!